Just like YouTube, Screencast.com now allows viewers to leave comments below screencasts hosted on that site. This includes stuff created in Jing. More details are at the Screencast.com blog. While YouTube is more popular and free, you'll get much better video quality out of the screencasts you post on Screencast.com, and you can still embed outside the site. I still kinda prefer Viddler.com for my hosting needs.